Optical imaging of enzymatic activity
Chemical imaging through visualizing functioning enzymes in vivo can describe highly patient-specific responses, allowing for profound diagnosis and subsequent personalized therapy. Cancer patients today often require an extended and agonizing series of treatment attempts – a process that can be shortened by real-time responses focusing on the patient. Our project aims to develop intelligent chemical imaging nano-probes that are optimally sensitive, employing commonly used fluorescent molecules conjugated to gold nanoparticles. In addition to the optimal qualities of gold nanoparticles as non-toxic and highly viable CT imaging agents, extensive research also considers fluorescent conjugation using linkers cleavable by specific enzymes. The significant electric field of the nanoparticles affects nearby fluorescent molecules as a function of distance, allowing us to visualize enzyme cleavage or other environmental effects through changes in fluorescence. Using these concepts, we are constructing probes with superior abilities, including enhanced fluorescence and the capacity to detect combinations of enzymes or physiological conditions. We are currently using our probes for monitoring apoptosis, by visualizing caspase activity. The probes can have a dual role for therapeutic stem cells, as the gold enables CT tracking of the cells, and fluorescence allows monitoring the viability of the cells. Used on drug-treated cancer cells, these probes could provide real-time indication of drug efficacy in vivo. Our research involves the combination of several detection switches. Each switch can respond to different enzymes or physiological conditions, meaning that the combination of switches reflects responses more specific than any one alone. Our research will also allow the visualization of enzyme location and concentration in vitro and in vivo, and possibly only regions of specific combinations of enzymes. Besides serving as an important step toward improved personalized medicine, probes requiring multiple enzyme activation would serve as biological logic gates, which in the future could be used as both autonomous therapeutic agents and personalized treatments.